Certain fuel systems are sometimes subjected to extreme temperature variations which cause the fuel to expand and contract. One such fuel system is for an open cycle turbine engine of the type that may be used in connection with torpedoes and the like, and such a fuel system can be subjected to storage in tropic or arctic conditions which would cause the fuel to expand or contract substantially, thus causing harmful pressure levels and potential damage to the fuel system. As a result, expansion and contraction must be accommodated in a manner that will eliminate or reduce the possibility of damage to the fuel system.
For this purpose, it has been recognized that a thermal expansion reservoir can be utilized in an advantageous fashion. This allows the fuel in the fuel system to expand and contract within the reservoir so as to maintain pressure levels in the fuel system within safe parameters. However, while recognized as useful, it has remained to provide a thermal expansion reservoir that will operate in an entirely satisfactory fashion.
More particularly, a fuel system for a torpedo is stored in a primed condition. In order to provide a constant pressure system whereby fuel can expand and contract freely despite the extremes of the arctic or tropics, and yet withstand a transition from atmospheric pressure to very high pressures that are normally seen with current torpedo technology, the housing and seal means of a thermal expansion reservoir must cooperate in a fail-safe manner, even if subjected to long periods of storage before use. Additionally, the thermal expansion reservoir must operate in a relatively frictionless manner, must easily be disassembled for cleaning, and must be compact to easily conform to a small envelope in a torpedo.
Among the attempts to provide a thermal expansion reservoir are those disclosed in Mercier U.S. Pat. Nos. 4,234,017; 3,830,259; and 2,786,488. The Mercier patents disclose pressure vessels in the form of rigid containers having a pair of ports at their respective ends with deformable partitions or bladders for separating two fluids such as the gas or liquid under pressure in the container. Unfortunately, the Mercier '017, '259, and '488 patents all fail to provide a redundant seal, a largely expansible or contractible chamber, or a bladder that is capable of rolling in a frictionless manner.
Strugar U.S. Pat. No. 3,409,714 does disclose a collapsible inner container accommodating the refilling thereof. It does not, however, disclose a redundant seal, nor does it suggest a resilient bladder that is capable of rolling in a frictionless manner in the presence of extremes of pressure caused by thermal variations that can be experienced in arctic or tropic conditions. In fact, the principal purpose of the Strugar et al '714 device is to provide a fuel tank with complete containment of automobile system vapors.
Beremand U.S. Pat. No. 2,924,359 discloses an expulsion bag fuel tank for use in aircraft and missiles that is adapted to store a supply of fuel under pressure. It, however, could not accommodate rolling of a resilient bladder since it utilizes an inner collapsible expulsion bag that is supported by an apertured rigid inner tank liner. Moreover, the Beremand '359 patent does not disclose an integral redundant seal.
The present invention is directed to overcoming the above stated problems and accomplishing the stated objects by providing a thermal expansion reservoir which can be disassembled, provides redundant sealing, and has a resilient bladder capable of automatic and controlled frictionless roll-up action.